1. Field of the Invention
This invention relates to tone control devices and programs for electronic wind instruments.
This application claims priority on Japanese Patent Application No. 2005-213775, the content of which is incorporated herein by reference.
2. Description of the Related Art
In general, octave-changeover-blowing techniques are applied to air-reed instruments such as flutes and piccolos so as to produce two notes, both of which have the same tone but differ from each other in pitch with an octave therebetween, by fingering. FIG. 29B shows a fingering state for producing notes E (see a left-side bar in FIG. 29A) with first and second octaves; and FIG. 29C shows a fingering state for producing notes F (see a right-side bar in FIG. 29A) with first and second octaves. For example, a player blows a wind instrument by way of the fingering state of FIG. 29B as follows:
In order to produce a note E of the first octave, the player blows the wind instrument with a relatively weak breath. In order to produce a note E of the second octave the player blows the wind instrument with a relatively strong breath. Herein, the first and second octaves slightly differ from each other in terms of embouchure.
Various physical parameters regarding sound emission have been analyzed with respect to air-reed instruments such as organ pipes (see a doctoral thesis entitled “Study on Organ Pipe and Its Underwater Application” written by Shigeru Yoshikawa in 1985 for Tokyo Institute of Technology in Japan). FIG. 30 shows physical parameters regarding a sound-emission structure of an organ pipe. In the sound-emission structure, AF designates an air flow applied to an organ pipe; SL designates a slit; and EG designates an edge. As physical parameters, there are provided a jet initial velocity U(0) [m/s] at an outlet of the slit SL, a jet final velocity U(d) [m/s] at the edge EG, a slit-edge distance d [m], a jet transmission time τe [sec] between the slit SL and the edge EG, and an audio frequency fso [Hz]. FIG. 30 also shows a relationship (i.e., a jet flow distribution) between a distance x counted from the slit SL and a jet velocity U(x). As shown in FIG. 30, the jet velocity U(x) gradually decreases from the initial velocity (0) to the final velocity U(d).
The aforementioned doctoral thesis teaches that octaves of sounds produced by air-reed instruments such as flutes and organ pipes depend upon a present sound mode and a jet angle θe. The jet angle θe is calculated using the jet transmission time τe and the audio frequency fso (or an audio angular frequency ωso=2π·fso) in accordance with equation 1 as follows:θe=ωso×τe (where ωso=2π·fso)
In addition, the jet transmission time τe is calculated using the slit-edge distance d and the jet velocity U(x) in accordance with equation 2 as follows:
      τ    ⁢                  ⁢    e    =            ∫      0      d        ⁢                  1        /                  U          ⁡                      (            x            )                              ⁢                          ⁢              ⅆ        x            
The jet transmission time τe can be calculated using trapezoidal approximation instead of the aforementioned integral calculation. Suppose that Ui represents jet velocity [m/s] at a designated distance counted from the slit SL, i.e., x=i·Δx [m] (where i=1, 2, . . . , n), whereby the jet transmission time τe can be calculated in accordance with equation 3 as follows:
      τ    ⁢                  ⁢    e    =            ∑              i        =        1            n        ⁢                  ⁢                  (                  1          /          2                )            ⁢              (                              1            /                          U                              i                -                1                                              +                      1            /                          U              i                                      )            ⁢      Δ      ⁢                          ⁢      x      
The jet transmission time τe calculated by the equation 3 designates a hatching area Sd of a graph shown in FIG. 31. In order to improve the accuracy of the aforementioned calculation, it is preferable that Δx be sufficiently reduced to a value such as 0.1 [cm], and the jet velocity be detected at various positions respectively.
FIG. 32 show variations of octaves based on tone-generation modes and jet angles θe. FIG. 32 shows two tone-generation modes, i.e., a first mode and a second mode. In the first mode, a prescribed note is produced with a prescribed octave. In the second mode, the note, which is produced in the first mode, is produced with a one-octave-higher interval.
In FIG. 32, when a jet occurs at an initial velocity U(0) in a state S1, a first mode tone generation is started in a state S2 in which θe=3π/2. In a state S3 in which the jet angle θe gradually decreases in an order of π, 3π/4, . . . , and π/2, an audio frequency gradually increases so as to cause variations on the tone volume and tone color in an actual air-reed instrument, which is not specifically discussed in the aforementioned doctoral thesis. In a state S4 in which θe=π/2, a jump occurs from the first mode to the second mode, in other words, a one-octave-increase occurs. During a state S5 causing a jump, the audio frequency is doubled so that the jet angle θe is correspondingly doubled to suit π.
In a state S6 in which θe=π, second mode tone generation is started. In a state S7 in which the jet angle θe increases from πto 3π/2, the audio frequency gradually decreases so as to cause variations in the tone volume and tone color in an actual air-reed instrument, which is not discussed in the aforementioned doctoral thesis. In a state S8 in which θe=3π/2, a jump occurs from the second mode to the first mode, in other words, a one-octave-decrease occurs. During a state S9 causing a jump, the audio frequency decreases to a half so that the jet angle θe correspondingly decreases to a half to suit 3π/4. In the leftward direction in FIG. 32, the jet velocity U(x) increases, and the slit-edge distance d decreases.
The following factors are taught in a master's thesis (entitled “Experimental Study on Jet Flow Distribution and Sound Characteristics in Air-Reed Instrument” written by Keita Arimoto in 2002 for Kyushu Art and Technology College) with respect to the jet velocity distribution as shown in FIG. 33.    (a) As the jet initial velocity becomes high, the jet velocity U(x) becomes dampened greatly.    (b) As the jet initial velocity becomes low and the slit-edge distance d becomes short, it is possible to neglect dampening of the jet velocity U(x).
Conventionally, a variety of technologies have been developed with respect to electronic wind instruments. For example, Japanese Unexamined Patent Application Publication No. H06-67675 teaches a tone generation control device for controlling a physical-model tone generator simulating an air-reed instrument in response to manual operation of a keyboard. With respect to electronic wind instruments having mouthpieces being blown with breaths, Japanese Unexamined Patent Application Publication No. S64-77091 teaches that tone generation is controlled to be started and stopped upon detection of an air flow by use of a breath sensor; Japanese Unexamined Patent Application Publication No. H05-216475 teaches that musical tone characteristics are controlled and switched over in response to a breath intensity; Japanese Unexamined Patent Application Publication No. H07-199919 teaches that tone pitches are controlled in response to directions of breaths blown into a mouthpiece; and Japanese Unexamined Patent Application Publication No. 2002-49369 teaches that tone pitch information and tone volume information are produced based on a breath flow input into a mouthpiece, its velocity, and a total breath value, for example.
The aforementioned publications suffer from the following problems.
In the electronic wind instrument disclosed in Japanese Unexamined Patent Application Publication No. H06-67675, various pieces of control information regarding jet magnitude, jet velocity, and jet angle (or jet inclination) are produced based on key operation information produced by a keyboard, whereby the control information is converted into parameters which are then supplied to a physical-model tone generator. This may cause difficulty in realizing real-time musical performance in response to blowing.
In the other electronic wind instruments disclosed in the other publications described above, it may be possible to realize real-time musical performance in response to blowing; however, it is very difficult to realize octave-changeover-blowing techniques, which are applied to conventionally-known air-reed instruments such as flutes. It may be possible to realize octave-changeover-blowing techniques by applying the technology taught in the aforementioned doctoral thesis to the aforementioned electronic wind instruments. However, the following problems may occur irrespective of the teaching of the aforementioned technology of the doctoral thesis.    (1) In the realization of octave changeover control based on the present tone-generation mode and the jet angle θe, the aforementioned equation 1 needs an actual audio frequency being calculated and substituted therefor. In the case of an electronic wind instrument which differs from a natural wind instrument, it is very difficult to calculate an actual audio frequency in advance.    (2) In order to accurately calculate the jet transmission time τe, it is necessary to perform sensing regarding the jet velocity at prescribed positions. In actuality, it is very difficult to arrange a plurality of flow sensors along a jet flow path of an electronic wind instrument.
In order to solve the aforementioned problems, it is strongly demanded to provide a tone control device which is capable of simulating octave-changeover-blowing techniques (conventionally used in air-reed instruments) in electronic wind instruments. Herein, octave changeover control may be realized by means of the tone control device based on various pieces of information regarding the jet velocity, jet length (i.e., a distance between a jet outlet and an edge), and fingering state, which are detected in an electronic wind instrument. Herein, musical tones may be varied in octaves when strong blowing is applied to low-pitch ranges. This may cause a difficulty in producing musical tones having relatively high tone volumes without varying octaves thereof.
It may be possible to realize octave changeover control based on the jet length only in order not to cause octave variations due to the strength of breaths. This method may realize octave-changeover-blowing techniques by simply changing lip-edge distances of electronic wind instruments, wherein strong blowing applied to low-pitch ranges may not always cause octave variations. However, players who are accustomed to octave-changeover-blowing techniques by controlling the strength of breaths without changing lip-edge distances may experience inconveniences in which musical tones cannot always be changed in octaves by simply controlling the strength of breaths.
In order to produce a relatively high tone volume on a flute that is actually played in low-pitch ranges, the aforementioned tone control device cannot cope with such an execution because it has a relatively small range of control regarding the tone volume.
In actuality, a flute is played to produce a tone color including high-order overtones by changing the jet eccentricity (i.e., positional shifts of a jet at an edge in a vertical direction) in order to increase pitches in the sense of hearing. The aforementioned tone control device cannot cope with such an execution because it has a relatively narrow range of control regarding the tone color.
In actuality, a player playing a flute may compensate for variations of pitches due to changes of registers and breathing by changing an area of lips in contact with a blow hole, thus causing variations of embouchure such as internal blowing and external blowing. The aforementioned tone control device cannot cope with such an execution because it has a relatively small range of control regarding the tone pitch.